Hi Dimitri, Dimitri DELABROYE <dimitri.delabr...@inria.fr> skribis:
> In order to be more secure we did not want to export /var/guix with RW > rights, we cannot trust root on the nodes. Just so those unfamiliar with Grid’5000 understand: what’s special here is that users can spawn new nodes where they are root, but this root user is not trusted as an admin of the cluster as a whole. Thus, if /var/guix as we know it were NFS-exported read/write, anyone could fiddle with all of /var/guix/profiles/per-user. That’s the reason why Dimitri & co. came up with the idea of storing per-user profiles in each user’s home directory. Why home directories? Because there’s already machinery on G5K that arranges so that a node can NFS-mount nothing but the home directory of the user who reserved the node. Why not treat /var/guix/profiles/per-user/USER NFS shares in the same way as home directories, then? That’s an option, but that’d mean extra work for G5K, AIUI. > So for the user profile to > work we did the following: > - mount the user's home on the guix server > - instead of letting guix create the user's profile on > /var/guix/profiles/per-user we created symlink: ln -s /home/USER/.guix > /var/guix/profiles/per-user/USER > This way we can export /var/guix with RO rights and users can't see > each others profiles. The problem is that ‘gc-roots’ in (guix store roots) won’t traverse those /per-user/USER symlinks. Instead, it assumes they are symlinks to indirect roots. > Another way would be to have a parameter to configure the > /var/guix/profiles/per-user directory so the symlink mecanism would > not be needed. For example guix could directly write in the user > directory in /home/USER/.guix. In fact, it’s possible to use profiles other than the default profile, and those profiles can be anywhere on the file system. For instance, if you do: guix install -p ~/.guix/my-profile emacs the thing is installed in ~/.guix/my-profile; that profile does not show up in /var/guix/profiles, but it is seen as a GC root by the daemon, via /var/guix/gcroots/auto. Longer-term, we could imagine having a “private profile” option, where the default profile is managed this way instead of being visible in /var/guix/profiles/per-user. But obviously that needs more thought and it’s not an option to solve your immediate problem. As it stands, the simplest option I think would be handle NFS exports of /var/guix/profiles/per-user/USER just like exports of /home/USER. Thoughts? Ludo’.